Systems and methods for backing up data files

ABSTRACT

Disclosed are systems and methods for maintaining, in a storage system having a source storage system and target storage system, information from which a set of source data files stored on a storage system can be retrieved. In one embodiment, the method comprises storing baseline images of one or more source data files in target files of the target storage system. For a selected target storage time, locations in the source storage system where changes have been made since a previous target storage time are dynamically identified. Contents that occupy the locations are read and sent to the target storage system. The contents are stored in the target storage system together with associations of the contents with the locations.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation application under 37 C.F.R. §1.53(b)of pending prior application Ser. No. 10/675,399, filed Sep. 30, 2003 ofChristopher MIDGLEY et al., for SYSTEMS AND METHODS FOR BACKING UP DATAFILES. This Application is also related to U.S. patent applicationserial No. 09/465,408 (now U.S. Pat. No. 6,625,623), Ser. No. 09/465,411(now U.S. Pat. No. 6,526,418), Ser. No. 09/465,435 (now U.S. Pat. No.6,779,003), Ser. No. 09/465,436 (now U.S. Pat. No. 6,847,984), Ser. No.09/465,485 (now U.S. Pat. No. 6,460,055), Ser. No. 10/152,060 (now U.S.Pat. No. 6,704,755), and Ser. No. 11/743,875 (pending), which is acontinuation of U.S. patent application Ser. No. 10/320,762 (abandoned),the contents of which applications are expressly incorporated byreference herein in their entireties.

BACKGROUND

Some back up systems operate by having the network administratoridentify a time of day during which little or no network activityoccurs. During this time, a network administrator can allow a backupsystem and the data files stored on the computer network to bebacked-up, file by file, to a long term storage medium, such as a tapebackup system. Typically the network administrator will back up once aweek, or even once a day, to ensure that the back up files are current.Such a backup process can be a time consuming, labor intensive, andcumbersome. As computer networks generally operate twenty-four hours aday, seven days week, it can be difficult for a system/networkadministrator to identify a time period during which network resourcesmay be relegated to a back up procedure. Further, increased users andnumbers of changes on a regular daily basis diminishes the value of aback up system that operates once a week or once a day. Systems thatonly generate back up data periodically are thus of a reduced value.

In some alternate systems, a data server and a backup server canmaintain mirrored data files and backup files. For example, in one suchsystem, a data server can execute change requests on data files andtransmit the change requests to the backup server, and the backup servercan execute the change requests on the corresponding backup files tokeep the backup files mirrored to the data files. Such systems may beviewed as lacking efficiency in their use of data processing capacityand data storage capacity, as two copies of all files are generallyrequired.

SUMMARY

Methods for backing up data files are described. In one embodiment, themethods can include detecting changed locations in one or more datafiles, storing the contents of the changed locations at a storage time,and associating the stored contents with the storage time, the changedlocations, and one or more file identifiers identifying the one or moredata files.

The storage time can be based on an actual time, a time interval, and/oran event.

In one embodiment, the methods can further include generating a baselineimage prior to detecting the changed locations. The baseline image caninclude one or more of the data files and can be based on a snapshotimage, a file image, and/or a volume image.

Detecting changed locations in the data files can include using one ormore data integrity procedures to generate a summary of an image of thedata files. The data integrity procedures can include a cyclicredundancy check (CRC) procedure and/or an MD5 message digest procedure.

Detecting changed locations in the data files can include generating abaseline image of the data files and using a data integrity procedure togenerate a summary of the baseline image at a time prior to the storagetime, generating a second image of the data files and using the dataintegrity procedure to generate a summary of the second imagethereafter, and determining whether the data files include changedlocations based on the baseline summary and the second summary.

Detecting changed locations can include dynamically detecting thechanged locations.

Storing the contents can include selecting at least one memory to storethe contents. The memory can be distinct from a previously selectedmemory associated with a prior storage time.

For the described systems and methods, associating can includegenerating one or more indexes to associate the stored contents, therespective storage times, the respective changed locations, and therespective file identifiers. The indexes can include a first index tothe changed locations based on the file identifiers and a second indexto the stored contents based on the changed locations.

In one embodiment, the method can further include iteratively returningto detecting changed locations.

In one embodiment, the method can further include using the storedcontents to create a version of a selected one of the data files.

For the described systems and methods, using the stored contents tocreate a version of a selected data file can include querying theindexes to identify stored contents and respective changed locationsassociated with the selected data file and combining the identifiedstored contents with data from a baseline image associated with theselected data file. The indexes can be queried for each of the storagetimes associated with the version based on the file identifierassociated with the selected data file.

Querying the indexes can include determining that the changed locationsare the same for two or more different storage times and identifying thestored contents of the changed locations associated with the latest ofthe different storage times.

In one embodiment, the methods can further include coalescing data.

Coalescing data can include coalescing: two or more stored contentsassociated with the same file identifier and two or more differentstorage times, the respective changed locations associated with the twoor more coalesced contents, and the indexes to associate the coalescedcontents, the respective coalesced changed locations, the fileidentifier, and the latest of the different storage times.

Coalescing data can also include coalescing: two or more stored contentsassociated with the same file identifier and the same storage time, therespective changed locations associated with the two or more coalescedcontents, and the indexes to associate the coalesced contents, therespective coalesced changed locations, the file identifier, and thesame storage time.

Also described are processor programs for backing up data files. Theprocessor programs can be stored on a processor-readable medium. In oneembodiment, the processor programs can include instructions to cause aprocessor to: detect changed locations in one or more data files, storethe contents of the changed locations at a storage time, and associatethe stored contents with the storage time, the changed locations, andone or more file identifiers identifying the one or more data files.

Also described are systems for backing up data files. In one embodiment,the systems can include one or more data files, one or more servers incommunication with the data files, where one or more of the servers canbe configured to execute change requests on the data files, and one ormore agents in communication with the one or more servers, where the oneor more agents can be configured to: detect changed locations in the oneor more data files, store the contents of the changed locations at astorage time, and associate the stored contents with the storage time,the changed locations, and one or more file identifiers identifying theone or more files.

These and other features of the described systems and methods can bemore fully understood by referring to the following detailed descriptionand accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C schematically illustrate an exemplary system for backing updata files;

FIG. 2 schematically illustrates exemplary operations for a systemaccording to FIGS. 1A-1C;

FIGS. 3 and 4 schematically illustrates exemplary delta files andindexes for a system according to FIGS. 1A-1C and 2; and,

FIG. 5 schematically illustrates an exemplary display of a graphicaluser interface that can facilitate the described systems and methods.

DETAILED DESCRIPTION

Illustrative embodiments will now be described to provide an overallunderstanding of the systems and methods described herein. One or moreexamples of the illustrative embodiments are shown in the drawings.Those of ordinary skill in the art will understand that the systems andmethods described herein can be adapted and modified to provide devices,methods, schemes, and systems for other applications, and that otheradditions and modifications can be made to the systems and methodsdescribed herein without departing from the scope of the presentdisclosure. For example, aspects, components, features, and/or modulesof the illustrative embodiments can be combined, separated,interchanged, and/or rearranged to generate other embodiments. Suchmodifications and variations are included within the scope of thepresent disclosure.

Generally, the described systems and methods relate to backing up datafiles. In embodiments of the described systems and methods, one or moreagents can detect changed locations in one or more data files withrespect to an image of the data files. The agents can store the contentsof the changed locations at a storage time and can generate one or moreindexes to associate the stored contents with the storage time, thechanged locations, and one or more file identifiers identifying the datafiles associated with the changed locations. The agents can thusiteratively return to detecting and/or continue to detect changedlocations in the data files with respect to the image, at respectivetimes. Based on the image, the stored contents, and the indexes, theagents can recreate one or more versions of one or more of the datafiles including changed locations at one or more of the storage times.

FIGS. 1A-1C schematically illustrate an exemplary system for backing updata files. As shown in the embodiment of FIG. 1A, the system 100 caninclude first and second client data processing devices (“clients”) 110,120, first and second data server data processing devices (“dataservers”) 130, 140, and first and second backup server digital dataprocessing devices (“backup servers”) 150, 160. The first and seconddata servers 130, 140 and the first and second backup servers 150, 160can be associated with first and second data storage devices 135, 145and first and second backup storage devices 155, 165, respectively. Thedata servers 130, 140 can provide the clients 110, 120 with access(e.g., read and/or write access) to data files stored on the datastorage devices 135, 145, respectively, based on requests from theclients 110, 120. In some embodiments, the data servers 130, 140 canmaintain different types of data files on the data storage devices 135,145, respectively. For example, in one such embodiment, the data server130 can maintain email files on the data storage device 135, and thedata server 140 can maintain document files on the data storage device145. The clients 110, 120 can open, close, modify, and/or delete thedata files stored on the data storage devices 135, 145. The backupservers 150, 160 can backup changes in the data files stored on the datastorage devices 135, 145 to the backup storage devices 155, 165. In someembodiments, the backup servers 150, 160 and the backup storage devices155, 165 can be configured to store backed up data with different termsof data retention. For example, in one such embodiment, the first backupserver 150 and the first backup storage device 155 can store data for arelatively short term, while the second backup server 160 and the secondbackup storage device 165 can store data for a relatively long term. Inone such embodiment, the first backup storage device 155 can include oneor more magnetic disks, and the second backup storage device 165 caninclude one or more magnetic tapes. The terms of data retention can beselected by a user (e.g., a system administrator or another entity).

As shown in FIG. 1A, the clients 110, 120, the servers 130, 140, 150,160, and the storage devices 135, 145, 155, 165 can exchange data over adata communications network 105. The data communications network 105 caninclude one or more network nodes (e.g., the clients 110, 120, the dataservers 130, 140, and the backup servers 150, 160) that can beinterconnected by wired and/or wireless communication lines (e.g.,public carrier lines, private lines, satellite lines, etc.) that enablethe network nodes to communicate. The exchange of data (e.g., messages)between network nodes can be facilitated by network devices (e.g.,routers, switches, multiplexers, bridges, and gateways, etc.) that canmanipulate and/or route data from an originating node to a server noderegardless of dissimilarities in the network topology (e.g., bus, star,or token ring), spatial distance (local, metropolitan, or wide areanetwork), transmission technology (e.g., transfer controlprotocol/internet protocol (TCP/IP) or Systems Network Architecture),data type (e.g., data, voice, video, or multimedia), nature ofconnection (e.g., switched, non-switched, dial-up, dedicated, orvirtual), and/or physical link (e.g., optical fiber, coaxial cable,twisted pair, or wireless, etc.) between the originating and servernodes. The nodes can include a networking subsystem (e.g., a networkinterface card) to establish a communications link between the nodes.The communications link interconnecting the nodes can include elementsof a data communications network, a point to point connection, a bus,and/or another type of digital data path capable of conveyingprocessor-readable data.

As will be understood by those of ordinary skill in the art, in someembodiments, one or more nodes of the data communications network 105can be included in a local area network (“LAN”). For example withreference to FIG. 1A, in one such embodiment, the clients 110, 120, thedata servers 130, 140, the first backup server 150, the data storagedevices 135, 145, and the first backup storage device 155 can form orotherwise be included in a LAN. Such a LAN can include a publiclyaccessible or a private, i.e., non-publicly-accessible, LAN. In such anembodiment, the second backup server 160 and the second backup datastorage device 165 can be located remotely from the LAN and cancommunicate with one or more nodes of the LAN based on schemes known tothose of ordinary skill in the art. Alternatively, for example withreference to FIG. 1A, in some embodiments, the clients 110, 120, thedata servers 130, 140, and the data storage devices 135, 145 can form orotherwise be included in a LAN, and the first and second backup servers150, 160 and the associated backup storage devices 155, 165 can belocated remotely from the LAN.

The described systems and methods are not limited to network-basedsystems, and can be implemented on stand-alone systems. For example, insome embodiments, the systems and methods described herein can beimplemented on a stand-alone system that includes a digital dataprocessing device and a data storage device. The digital data processingdevice can include features of data servers and backup servers asdescribed herein, and the data storage device can include storage fordata files and backed-up data.

The digital data processing devices 110, 120, 130, 140, 150, 160 caninclude a personal computer, a computer workstation (e.g., Sun,Hewlett-Packard), a laptop computer, a mainframe computer, a servercomputer, a network-attached storage (NAS) device, a handheld device(e.g., a personal digital assistant, a Pocket Personal Computer (PC), acellular telephone, etc.), an information appliance, and/or another typeof generic or special-purpose, processor-controlled device capable ofreceiving, processing, and/or transmitting digital data. As will beunderstood by those of ordinary skill in the art, a processor can referto the logic circuitry that responds to and processes instructions thatdrive digital data processing devices and can include, withoutlimitation, a central processing unit, an arithmetic logic unit, anapplication specific integrated circuit, a task engine, and/orcombinations, arrangements, or multiples thereof.

As shown in FIG. 1A, the storage devices 135, 145, 155, 165 can storedata files that can be maintained by the servers 130, 140, 150, 160,respectively. As used herein, the term data files can be understood toinclude files having types and formats of data known to those ofordinary skill in the art. For example, the term data files can includeapplication files, data files, executable files, object files, programfiles, operating system files, registry files, and other types of datafiles known to those of ordinary skill in the art, with such examplesprovided for illustration and not limitation. In some embodiments, theterm data files can be understood to include one or more portions ofdata files. For example, in some embodiments, the term data files can beunderstood to include data objects within data files, such asattachments (e.g., attachments to email files), records (e.g., recordsin an email file), and data rows and tables (e.g., data rows and tablesin a structured query language (SQL) database file), with such examplesbeing provided for illustration and not limitation. The storage devices135, 145, 155, 165 can include, for example, volatile and/ornon-volatile memory and/or storage elements, such as a random accessmemory (RAM), a hard drive (e.g., an internal or external hard drive), amagnetic disk, a magnetic tape, a compact disk (CD), a digital videodisk (DVD), a redundant array of independent disks (RAID), a removablememory device. In some embodiments, the storage devices 135, 145, 155,165 can include storage devices networked via a network storage topologyknown to those of ordinary skill in the art, such as, but not limitedto, network-attached storage (NAS) and/or storage area networking (SAN)topologies. In some embodiments, such as the embodiment shown in FIG.1A, the storage devices 135, 145, 155, 165 can be physically separatefrom the servers 130, 140, 150, 160, respectively. Alternatively and/orin combination, in some embodiments, one or more of the storage devices135, 145, 155, 165 can be physically integrated into one or morerespective servers 130, 140, 150, 160. For example, in one suchembodiment, storage device 135 can be integrated into server 130. Insome embodiments, one storage device can be associated with two or moreservers.

FIG. 1B schematically illustrates features of an exemplary data serverand an associated data storage device. As shown in FIG. 1B, the dataserver 200 can include a schedule agent 210, a storage space agent 215,a status agent 225, a policy coordinator agent 230 and one or morepolicies 235, a command coordinator agent 240 and one or more commands245, an index agent 250, a file system interface 255, an image agent260, and a detecting agent 265. As used herein, the term agent can referto one or more software processes executing on the data server 200, andthe term policy can refer to an operation (such as a backup operation, arestore operation, and a coalescence operation) to be performed by theagents of the data server 200. A policy can include data based on and/orotherwise associated with one or more data files (e.g., a list of thedata files affected by the policy) and times of executing the policy. Asfurther described herein, a policy can be generated by a user (e.g., asystem administrator or another entity). Although the features of thedata server 200 (and the features of the backup server 300 shown in FIG.1C) are shown as performing different functions, those of ordinary skillin the art will understand that the features of the data server 200(and, separately, the features of the backup server 300) can be combinedor otherwise modified to form different features and should beinterpreted in an illustrative and non-limiting manner.

As shown in the embodiment of FIG. 1B, the data server 200 can beassociated with a data storage device 270 that can store one or moredata files 275 in a format such as a directory and sub-directorystructure, although other formats can be employed. The schedule agent210 can provide messages including time data that can be used by thepolicy coordinator agent 230 and/or other agents to initiate one or moreactions. For example, as described further herein, in one embodiment,the schedule agent 210 can provide a message to the policy coordinatoragent 230 indicating that a time included in a policy 235 for performingan action has been reached. The storage space agent 215 can determinethe quantity of available storage space on the data storage device 270.The status agent 225 can provide status information (e.g., errormessages and/or informational messages) to one or more agents of thedata server 200. The policy coordinator agent 230 can manage thepolicies 235 on the data server 200 and can specify an operation to beexecuted (e.g., a backup operation, a restore operation, and acoalescence operation). The command coordinator agent 240 can execute anoperation specified by the policy coordinator agent 230. For example,the command coordinator agent 240 can generate commands 245 (e.g.,backup, restore, and coalescence commands) for executing an operationspecified by the policy coordinator 230. The index agent 250 cangenerate one or more indexes to locate backed-up data. For example, inone embodiment, the index agent 250 can generate two indexes forlocating backed-up data based on the data files 275 stored on the datastorage device 270. The file system interface 255 can provide aninterface to the data files 275 stored on the data storage device 270.The image agent 260 can generate an image of one or more of the datafiles 275 stored on the data storage device 270. The detecting agent 265can detect changed locations in one or more of the data files 275 storedon the data storage device 270 with respect to an image of the datafiles. As provided previously herein, the illustrated embodiments aremerely exemplary, and accordingly, agents 210, 225, 230, 240, 250, 260,265 can be combined, separated, and/or rearranged in differentembodiments.

FIG. 1C schematically illustrates features of an exemplary backup serverand an associated backup storage device. As shown in FIG. 1C, the backupserver 300 can include one or more agents similar to those shown in FIG.1B. These agents are denoted by reference numerals that differ byincrements of 100 with respect to the reference numerals of the agentsshown in FIG. 1B. Also, the backup server 300 can include a delta agent380 and a storage management agent 385. The delta agent 380 can managedata stored on backup storage device 370, such as data associated with abackup of the data files stored on data storage device 270. The storagemanagement agent 385 can provide input and output (e.g., asynchronousinput and output) to the backup storage device 370.

As will be understood by those of ordinary skill in the art, thedescribed systems and methods are not limited to a particularconfiguration of clients, data servers, backup servers, and storagedevices, and can be implemented on systems different than those shown inFIGS. 1A-1C. For example, the described systems and methods can beimplemented on configurations including one or more clients, one or moredata servers, one or more data storage devices, one or more backupservers, and one or more backup storage devices. Those of ordinary skillin the art will also understand that the functions of one or more of thefeatures of the data server 200 and backup server 300 can be distributedamong two or more features. For example, the functions of the imagingagent 260 of the data server 200 can be distributed between agentsresiding on the data server 200 and the backup server 300. Also forexample, the functions of the imaging agent 260 of the data server 200can be distributed among two or more imaging agents associated withdifferent groupings of the data files 275 stored on the data storagedevice 270.

FIG. 2 schematically illustrates a portion of the exemplary system 100shown in FIGS. 1A-1C. As shown in FIG. 2, the illustrated portion of theexemplary system 100 can include a data server 400 and an associateddata storage device 470 and a backup server 500 and an associated backupstorage device 570. The data server 400 and the backup server 500 caninclude features similar to those described herein with respect to FIGS.1A-1C. Some of these features are denoted in FIG. 2 with referencenumerals that differ by increments of 100 with respect to the referencenumerals of FIGS. 1B and 1C. As will be understood by those of ordinaryskill in the art, the data server 400 and the backup server 500 canexchange data based on a client/server model, in which the data server400 can represent the client portion of the model and the backup server500 can represent the server portion of the model.

Exemplary operations for a system according to FIGS. 1A-1C will now bedescribed with reference to FIG. 2. The operations shown in FIG. 2 canbe initiated by one or more agents residing on the data server 400and/or one or more agents residing on the backup server 500. Those ofordinary skill in the art will understand that the exemplary operationsshould be interpreted in an illustrative and non-limiting manner.

An overview of an exemplary backup operation for a system according toFIGS. 1A-1C will now be provided with reference to FIG. 2. For purposesof illustration, the exemplary backup operation will be described withrespect to initiation by agents residing on the data server 400. Basedon a backup command 445 from a command coordinator agent 440, theimaging agent 460 can generate a byte-level image 478 of the data files475 stored on the data storage device 470. As shown in FIG. 2, the datastorage device 470 can store one or more data files 475 which caninclude a hierarchical structure, such as the illustrated directory andsubdirectory structure. In some embodiments, the byte-level image 478can be stored on the data storage device 470. Alternatively and/or incombination, in some embodiments, the byte-level image 478 can be storedon the backup storage device 570. Substantially contemporaneously withand/or subsequent to generation of the image 478, the detecting agent465 can detect, on a byte level, changed locations in the data files 475with respect to the image 478. The data server 400 (e.g., the commandcoordinator agent 440, the detecting agent 465, and/or another agent onthe data server 400) can provide the changed locations to the backupserver 500, and, at a storage time, such as the storage time t₀ shown inFIG. 2, the delta agent 580 can store the contents of the changedlocations in a delta file 590 on the backup storage device 570.Alternatively and/or in combination, the backup server (e.g., thecommand coordinator agent 540, the delta agent 580, and/or another agenton the backup server 500) can retrieve the changed locations from thedata server 400. Substantially contemporaneously with and/or subsequentto generation of the delta file 590, the index agent 450 and/or 550 canassociate the stored contents in the delta file 590 with the storagetime t₀, the changed locations, and one or more file identifiersidentifying the data files 475 including the detected changed locations.For example, as shown in FIG. 2, the index agent 450 and/or 550 cangenerate a first index 592 to the changed locations based on the fileidentifiers and a second index 594 to the stored contents based on thechanged locations. As shown in the embodiment of FIG. 2, the first andsecond indexes 592, 594, respectively, can be stored on the backupstorage device 570. Alternatively and/or in combination, the first andsecond indexes 592, 594, respectively can be stored on the data storagedevice 470. The detecting agent 465 can iteratively return to detectingand/or continue to detect changed locations in the data files 475 withrespect to the image 478, and the delta agent 580 can generate deltafiles 590′, 590″ at subsequent storage times, such as the times t₁, t₂shown in FIG. 2. The index agent 450 and/or 550 can generate first andsecond indexes associated with the delta files, denoted as 592′, 592″and 594′, 594″, respectively. As described further herein, the image478, the delta files 590, and the associated first and second indexes592, 594 can be used to create a version of a data file includingchanged locations at one or more of the storage times t₀, t₁, and t₂.

Data included in one or more of the delta files 590, first indexes 592,and second indexes 594 can be compressed and/or encrypted based onschemes known to those of ordinary skill in the art.

Some features of the exemplary backup operation shown in FIG. 2 will nowbe described. The backup operation can be initiated by a request tobackup a data file stored on the data storage device 470. In someembodiments, a scheduling agent 410 and/or 510 can provide a messageindicating that a time or an event (e.g., condition satisfied) includedin a backup policy 435 and/or 535 has occurred. A backup policy 435and/or 535 can include data based on data files for which to detectchanged locations (which are referred to herein as “policy data files”)and storage times at which to store the contents of the changedlocations. The storage times can be based on times, such as actual times(e.g., times as measured by a clock on a server, such as the data server400 and/or the backup server 500) and time intervals (e.g., periodictime intervals as measured by a clock on a server), and/or events (e.g.,events specified by a system administrator or another entity). Forpurposes of illustration, the policy data files in FIG. 2 are designatedas the data files 475 stored on the data storage device 470. Those ofordinary skill in the art will understand that the policy data files caninclude one or more of the data files 475 stored on data storage device470. Those of ordinary skill in the art will also understand that thedescribed systems and methods can be configured to concurrently executemultiple policies associated with different policy data files.

Based on a request to backup the policy data files 475 and/or a messagefrom a scheduling agent 410 that a time or an event included in a backuppolicy 435 has occurred, a policy coordinator agent 430 can determinewhether an image for the policy data files already exists, i.e., waspreviously generated. As used herein, the term image can be understoodto include a copy of the policy data files 475 at a previous time. Thepolicy coordinator agent 430 can determine whether the image of thepolicy data files exists based on schemes known to those of ordinaryskill in the art. Based on determining that an image of the policy datafiles does not exist, the policy coordinator agent 430 can instruct thecommand coordinator agent 440 to generate an image of the policy datafiles 475, and the command coordinator agent 440 can instruct the imageagent 460 to generate an image of the policy data files 475. Forexample, as shown in the embodiment of FIG. 2, the image agent 460 cangenerate an image 478 of the policy data files 475 and store the image478 on the data storage device 470.

The image agent 460 can generate one or more different types of images.In some embodiments, the image agent 460 can generate a snapshot image478 of the policy data files 475. As used herein, the term snapshotimage 478 can be understood to include the contents of the policy datafiles 475 and their interrelationships, e.g., the directory andsub-directory structure shown in FIG. 2. Alternatively and/or incombination, in some embodiments, the image agent 460 can generate oneor more file images (e.g., images of one or more of the policy datafiles 475) and/or one or more volume images, as the term volume imagesis understood by those of ordinary skill in the art. The image agent 460can generate the image 478 in a transactional safe state of the policydata files 475. For example, prior to generation of the baseline image478, the command coordinator agent 440 can instruct the data server 400and/or the data storage device 470 to place the policy data files 475into a transactional safe state. As will be understood by those ofordinary skill in the art, a transactional safe state refers to a stateof a data file in which changes to a data file are prohibited at leasttemporarily. The transactional safe state of the policy data files 475can be released after generation of the image 478.

In some embodiments, the command coordinator agent 440 can command theindex agent 450 to use one or more data integrity procedures to generatea summary or digest of the image 478. The data integrity procedures canbe based on one or more of a Cyclic Redundancy Check (CRC) algorithm,the MD5 message digest algorithm, and other digest algorithms known tothose of ordinary skill in the art. The index agent 450 can associatethe summary with the image 478 and can store the summary in the datastorage device 470. In some embodiments, the index agent 450 cangenerate a summary of one or more portions of the image 478. Forexample, in one such embodiment, the index agent 450 can generatesummaries of directories and/or subdirectories included in the image478. Also for example, in one such embodiment, the index agent 450 cangenerate summaries of one or more of the policy data files 475 includedin the image 478.

In the following discussion, references will be made to baseline imagesand summaries and second images and summaries. As used herein, the terms“baseline” and “second” can refer to a relative time relationship, inwhich baseline indicates association with an earlier time, and secondindicates association with a later time.

Based on a baseline image 478 for the policy data files 475 beinggenerated and/or otherwise identified, the policy coordinator agent 430can instruct the command coordinator agent 440 to backup the policy datafiles 475, and the command coordinator agent 440 can instruct thedetecting agent 465 to detect changed locations in the policy data files475. In some embodiments, the detecting agent 465 can include a filesystem filter. As will be understood by those of ordinary skill in theart, a file system filter can include a driver that interacts with anoperating system via a kernel interface and that can intercept andcommunicate requests (e.g., input/output request packets (IRPs)) from anoperating system to a file system. Alternatively and/or in combination,in some embodiments, the detecting agent 465 can include a file scanningagent. In some embodiments, the detecting agent 465 can include a filesystem filter and a file scanning agent as part of a redundancy scheme.For example, the detecting agent 465 can detect changes by default withthe file system filter and, based on a failure of the file systemfilter, with the file scanning agent. In some embodiments, the detectingagent 465 can detect changed locations on a byte-level and/or a diskblock-level.

As will be understood by those of ordinary skill in the art, thedescribed systems and methods are not limited to detecting agents 465that include a file system filter and/or a file scanning agent and caninclude detecting agents 465 that are configured to detect changesand/or changed locations in data files 475 based on other schemes foraccomplishing the same.

In embodiments in which the detecting agent includes a file systemfilter, the detecting agent can intercept requests (e.g., writerequests) from an operating system of the data server 400 to the policydata files 475 stored on the data storage device 470. In one suchembodiment, the detecting agent 465 can provide messages that describechanges to the policy data files 475. For example, the detecting agent465 can provide messages including data based on changed locations inthe policy data files 475. The data can include file identifiersidentifying files having changed locations and the byte-level changedlocations. The detecting agent 465 can provide the messages dynamically,i.e., substantially contemporaneously with the changes to the policydata files 475. In embodiments in which the detecting agent 465 includesa file system filter, therefore, the detecting agent 465 can provide thecommand coordinator agent 440 with file identifiers identifying one ormore policy data files 475 having changed locations and thecorresponding byte-level changed locations.

In embodiments in which the detecting agent 465 includes a file scanningagent, the detecting agent 465 can scan the policy data files 475 forchanged locations based on commands from the command coordinator agent440. In one such embodiment, the image agent 460 can generate a secondimage of the policy data files 475, the index agent 450 can generate asecond summary of the second image, and the detecting agent 465 can usethe second summary and the baseline summary to determine whether thepolicy data files 475 include changed locations. For example, thedetecting agent 465 can compare the second summary with the baselinesummary to determine whether one or more of the policy data files 475includes changed locations. Generally, differences between the baselinesummary and the second summary can indicate that one or more of thepolicy data files 475 includes changed locations. As will be understoodby those of ordinary skill in the art, the detecting agent 465 cancompare multiple second summaries with multiple corresponding baselinesummaries to identify policy data files 475 including changed locations.For example, the detecting agent 465 can compare summaries in adescending hierarchical manner, such as directory summaries,subdirectory summaries, and data file summaries, to identify policy datafiles 475 including changed locations. Based on identifying one or morepolicy data files 475 including changed locations, the detecting agent465 can compare the second images of the policy data files having thechanged locations with the corresponding baseline images to identify thechanged locations. In embodiments in which the detecting agent 465includes a scanning agent, therefore, the detecting agent 465 canprovide the command coordinator agent 440 with file identifiersidentifying one or more policy data files 475 having changed locationsand the corresponding byte-level changed locations.

At a storage time included in the backup policy 435 and/or 535, such asthe storage time t₀ shown in FIG. 2, the data server 400 (e.g., thedetecting agent 465, the command coordinator agent 440, and/or anotheragent on the data server 400) can provide to the backup server 500(e.g., the command coordinator agent 540, the delta agent 580, and/oranother agent on the backup server 500) the contents of the changedlocations, and the delta agent 580 can store the contents in a deltafile 590 on the backup storage device 570. Alternatively and/or incombination, the backup server 500 can retrieve from the data server 400the contents of the changed locations. Generally, the contents of thechanged locations detected by the detecting agent 465 can be copied fromthe policy data files 475 stored on the data storage device 470 to thedelta file 590 stored on the backup storage device 570. The delta agent580 can store the contents in a delta file 590 that can be uniquelyassociated with the storage time, i.e., in a memory location that isdifferent than a memory location associated with a different storagetime. As shown in FIG. 2, the index agent 450 and/or 550 can generatethe first and second indexes 592, 594, respectively, substantiallycontemporaneously with and/or subsequent to the generation of the deltafile 590.

In some embodiments, the command coordinator agent 440 and/or 540 caninclude summaries of the contents of the changed locations in the secondindexes 594. For example, the command coordinator agent 440 and/or 540can command the index agent 450 and/or 550 to generate summaries of thecontents of the changed locations being stored in the delta file 590.The detecting agent 465 can use the summaries to detect subsequentlychanged locations in the policy data files 475 based on schemesdescribed herein.

Substantially contemporaneously with and/or subsequent to the storagetime t₀, the detecting agent 465 can iteratively return to detectingand/or continue to detect changed locations in the policy data files475. As shown in FIG. 2, delta files 590 and associated first and secondindexes 592, 594 can be generated at storage times t₁ and t₂ that arelater than the storage time t₀ based on schemes described herein. Aspreviously indicated, a delta file 590 can represent changed locationsin the policy data files 475 at a storage time t₁ with respect to thebaseline image 478.

FIG. 3 schematically illustrates features of exemplary delta files andindexes for a backup operation of a system according to FIGS. 1A-1C and2. As shown in FIG. 3, a first index 600 can include data based on fileidentifiers 610 for policy data files including changed locations andlocations 620, in a second index 640, of those changed locations. Thelocations 620 can be provided in the form of block offsets in the secondindex 640. As shown in FIG. 3, the second index 640 can include databased on the changed locations 650 and locations 660, in a delta file670, of the contents of the changed locations. The locations 660 can beprovided in the form of block offsets in the delta file 670. The deltafile 670 can include contents 680 of the changed locations 650. Forpurposes of illustration, the delta file 670 includes an explanatorycolumn 690 showing the changed locations 650 and file identifiers 610associated with the contents 680.

In some embodiments, the changed locations 650 and the contents 680 canbe grouped consecutively. As shown in the second index 640, the changedlocations 650 can be grouped consecutively based on the file identifierassociated with the changed locations 650. For example, the changedlocations 650 a associated with file A 610 a can be groupedconsecutively, and the changed locations 650 b associated with file B610 b can be grouped consecutively. As shown in the delta file 670, thecontents 680 can be grouped consecutively based on the changed locations650 associated with the contents 680. For example, the contents 680 aassociated with the changed locations 650 a can be groupedconsecutively, and the contents 680 b associated with the changedlocations 650 b′ can be grouped consecutively. Although FIG. 3 showsthat the changed locations 650 and the contents 680 can be storedconsecutively, those of ordinary skill in the art will understand thatthe described systems and methods are not limited to consecutive storageof the changed locations 650 and/or the contents 680, and thatnon-consecutive storage schemes for the changed locations and/or thecontents different than those described herein can be used.

An exemplary restore operation for a system according to FIGS. 1A-1Cwill now be described with reference to FIG. 2. For purposes ofillustration, the exemplary restore operation will be described withrespect to restoring a version of a policy data file 476 by agentsresiding on the backup server 500. Those of ordinary skill in the artwill understand that the exemplary restore operation should beinterpreted in an illustrative and non-limiting manner and that anoperation similar to that described herein can be used to restore two ormore policy data files.

The exemplary restore operation shown in FIG. 2 can be triggered by arequest to restore a version of the policy data file 476. In someembodiments, a scheduling agent 410 and/or 510 can provide a messageindicating that a time or an event included in a restore policy 435and/or 535 has been reached. A restore policy 435 and/or 535 can includedata based on versions of data files to restore and restore times atwhich to restore the versions. The restore times can be based on times,such as actual times and time intervals, and/or events.

Based on a request to restore a version of the data file 476 and/or amessage from a scheduling agent 510, a policy coordinator agent 530 caninstruct a command coordinator agent 540 to create the version 600(e.g., open a new file for the version 600), write to the version 600the baseline image 478 associated with the data file 476, and determinea delta file range and/or a storage time range for the version 600. Aswill be understood by those of ordinary skill in the art, the version600 of the data file 476 can be associated with a version time, e.g., apast time. Based on the version time, the command coordinator agent 840can determine the delta file range and/or the storage time range for theversion 600. The storage time range can include storage times that areearlier than and/or substantially equal to the version time, and thedelta file range can include delta files associated with times that areearlier than and/or substantially equal to the version time. For examplewith reference to FIG. 2, for a version time t₁′, where t₂<t₁′<t₁, thestorage time range can include the storage times t₀ and t₁ and the deltafile range can include the delta files 590 and 590′.

FIG. 4 shows exemplary delta files and indexes for a restore operationfor a system according to FIGS. 1A-1C and 2. For purposes ofillustration, the storage time range for the version 600 of the datafile 476 to be restored includes the storage times t₀, t₁, and t₂, thedelta file range includes the delta files 790, 790′, and 790″, and thefile identifier for the data file 476 is “file A.” The commandcoordinator agent 540 can query the first indexes associated with thedelta file range for the version 600 (i.e., the first indexes 792, 792′,792″) to determine whether one or more the first indexes includes thefile identifier file A. Based on a first index including a fileidentifier file A, the command coordinator agent 540 can query thecorresponding second index and delta file to identify the changedlocations and the contents of the changed locations. As shown in FIG. 4,the first indexes 792 and 792″ include file identifiers for file A,while the first index 792′ does not include a file identifier for fileA. The first indexes 792, 792″ indicate that changes for file A werestored at storage times t₀ and t₂, while the first index 792′ indicatesthat changes for file A were not stored at storage time t₀. Based on thesecond indexes 794, 794″ and the delta files 790, 790″ corresponding tothe first indexes 792, 792″, the command coordinator agent 540 can writeto the version 600 the contents of the changed locations for file A. Asshown in FIG. 4, the contents in delta files 790, 790″ can be written tothe version 600. The command coordinator agent 540 can combine thecontents of the changed locations with the data from the baseline imagepreviously included in the version 600 (e.g., the command coordinatorcan overwrite one or more portions of the baseline image with thecontents of the changed locations). The backup server 500 (e.g., thecommand coordinator agent 540) can provide the recreated version 600 tothe data server 400 (e.g., the command coordinator agent 440).

As previously described, in some embodiments, a version of a data filecan be restored based on a backup server 500 (e.g., one or more agentsresiding on the backup server 500) writing backed-up data associatedwith the version of the data file to a version 600 and providing therecreated version 600 to a data server 400 (e.g., to one or more agentsresiding on the data server 400). Alternatively and/or in combination,in some embodiments, a version of a data file can be restored based onthe backup server 500 providing the backed-up data associated with theversion of the data file (e.g., backed-up data based on the delta files590, first indexes 592, and/or second indexes 594 associated with theversion of the data file) to the data server 400, and the data server400 can use the image 478 and the backed-up data to recreate a version600 of the data file. In such embodiments, the backup server 500 canprovide the data server 400 with relevant portions of relevant deltafiles, first indexes, and second indexes for recreating a version of adata file, and the data server 400 can open the version and write to theversion the relevant portions of the backed up data and the image 478.The data server 400 can combine the relevant portions of the backed updata and the image 478. For example, the data server 400 can overwriteportions of the image 478 with corresponding portions of more recentbacked-up data.

A version of a data file can be restored to one or more memory locationson one or more servers. For example, in some embodiments, a restoredversion of a data file can be associated with the same memory locationas an original version, and the original version can be moved to and/orotherwise associated with a different memory location. Alternativelyand/or in combination, in some embodiments, a restored version of a datafile can be associated with one or more different memory locations thanan original version. For example, a restored version of a data file canbe associated with a different directory than an original version. Alsofor example, a restored version of a data file can be restored to one ormore different storage devices (e.g., different storage devices on aLAN). A restored version of a data file can be associated with a namebased on schemes known to those of ordinary skill in the art.

In one embodiment of the disclosed methods and systems, a coalescingprocess as provided herein can be employed to simulate a tape rotationscheme where a coalesced file, for example, can be associated with avirtual “tape.” The number of virtual tapes, and hence, associated tapefile(s) (e.g., a file derived using coalescence) may vary based on auser selection, administrator configuration, etc., and can depend on,for example, storage capacity, back up time/interval, and other factors.In some embodiments, one or more user interfaces can be provided toprovide a tape rotation experience to a user and/or system administratorvia the virtual tapes and the associated tape file(s). Access to a filecan thus be provided based on an associated tape identity.

In one example of a virtual tape embodiment, a user and/or systemadministrator can determine a time t₀ generate a “tape” file, and thusdetermine a time for coalescence. In some embodiments, this manualdetermination of the time may override and/or be performed in additionto otherwise scheduled coalescing processes as provided herein. In someembodiments, a user and/or system administrator may be limited to thenumber of “tape” files, and thus, the creation of a new tape file mayoverwrite and/or otherwise cause to be inaccessible, the oldest and/oranother designated tape file within the limited number of tape files. Itcan be understood that the aforementioned methods for providing avirtual tape scheme can be employed via one or more user interfaces thatcan allow the user/system administrator to perform the features asprovided herein. For example, the user/system administrator can beprovided an interface that may show virtual tape identifiers, associatedfile identifiers, file information (e.g., time of creation, user IDassociated with the creation, storage location, coalescence information,etc.), to allow the user/system administrator to make selections and/ordesignations as provided herein.

With continuing reference to FIG. 2, in some embodiments, the commandcoordinator agent 540 can process delta files, first indexes, and/orsecond indexes in a time order. In one embodiment including a reversetime processing order, the command coordinator agent 540 can determinewhether changed locations for a file identifier at two or more storagetimes are the same. For example, the command coordinator agent 540 candetermine whether changed locations associated with a file identifier intwo or more second indexes are the same. Based on the changed locationsbeing the same, the command coordinator agent 540 can write to theversion 600 the stored contents of the changed locations associated withthe latest storage time, i.e., the stored contents in the delta fileassociated with the latest storage time. For example with reference toFIG. 4, the second indexes 792 and 792″ indicate that block 10 of file Achanged at storage time t₀ and, later, at storage time t₂. In someembodiments, the command coordinator agent 540 can write to the version600 the contents of block 10 from delta file 790″ and ignore thecontents of block 10 from delta file 790. Those of ordinary skill in theart will understand that the described systems and methods are notlimited to a processing time order of the delta files, first indexes,and second indexes, and that other processing orders and/or schemes canbe used within the scope of the present disclosure.

As previously described herein, in some embodiments, a version of a datafile can be restored based on identifying a delta file range associatedwith the version and querying delta files and first and second indexesassociated with the delta file range to identify changed locations andcontents of the changed locations for the version. In embodiments inwhich the detecting agent 465 includes a file system filter, the versioncan be restored based on the backup server 500 (e.g., one or more agentson the backup server 500) providing the relevant backed-up data for theversion (e.g., the relevant portions of the relevant delta files andindexes for the delta file range and file identifier associated with thedata file) to the data server 400 (e.g., one or more agents on the dataserver 400), and the data server 400 can combine the contents of thebacked-up data with the changes detected by the detecting agent 465 attimes later than the latest storage time associated with delta filerange but earlier than and/or contemporaneous with the version time. Forexample, with reference to FIG. 2, for a version time t₁′ that occursbetween two storage times, e.g., t₂<t₁′<t₁, the detecting agent 465 canprovide changed locations occurring subsequent to the storage time t₁and earlier than and/or contemporaneous with the version time t₁′.

An exemplary coalescence operation for a system according to FIGS. 1A-1Cwill now be described with reference to FIG. 2. For purposes ofillustration, the coalescence operation will be described with respectto initiation by agents residing on the backup server 500. Those ofordinary skill in the art will understand that the exemplary coalescenceoperation should be interpreted in an illustrative and non-limitingmanner and that an operation similar to that described herein can beused to coalesce different types of backed up data, e.g., delta files,first indexes, and/or second indexes.

The exemplary coalescence operation shown in FIG. 2 can be triggered bya request to coalesce one or more portions of the backed up data storedon the backup storage device 570. In some embodiments, a schedulingagent 410 and/or 510 can provide a message indicating that a time or anevent included in a coalescence policy 435 has been reached. Acoalescence policy can identify backed up data to be coalesced and timesat which to coalesce the backed up data. The coalescence times can bebased on times, such as actual times and time intervals, and/or events.In some embodiments, the events can be based on available storage space.For example, a coalescence operation can be triggered based on anavailable storage space on the backup storage device 570 dropping belowa threshold. Based on a request to coalesce and/or a message from thescheduling agent 510, the policy coordinator agent 530 can instruct thecommand coordinator agent 540 to coalesce one or more portions of thebacked up data stored on the backup storage device 570.

In some embodiments, the command coordinator agent 540 can coalescestored contents within a single delta file. As previously described, insome embodiments, the detecting agent 465 can include a file systemfilter that can detect changed locations as the changed locationshappen, i.e., substantially contemporaneously with the changedlocations. For example, the file system filter can detect changes in thesame changed location of a data file at different times between storagetimes. A delta file can thus include multiple instances of storedcontents corresponding to the same changed locations of the same datafile. In some embodiments, the command coordinator agent 540 cancoalesce, i.e., merge, stored contents in a single delta file that areassociated with the same changed locations of a data file, so that thecoalesced delta file includes one instance of a changed location of adata file. Also for example, a file system filter can detect portions ofconsecutive changed locations at different times between storage times.A delta file can thus store contents of consecutive changed locations ina data file at non-consecutive locations. In some embodiments, thecommand coordinator agent 540 can coalesce, i.e., concatenate, storedcontents in a single delta file that are associated with consecutivechanged locations for a data file, so that the stored contents in thecoalesced delta file are stored consecutively. Based on coalescing thestored contents in the delta file, the command coordinator agent 540 cancoalesce the corresponding first and second indexes to associate thecoalesced contents in the coalesced delta file with the coalescedchanged locations and the coalesced file identifiers.

Alternatively and/or in combination, in some embodiments, the commandcoordinator agent 540 can coalesce, i.e., merge, two or more delta filesassociated with different storage times t₀ generate a coalesced deltafile. As shown in FIG. 4, two or more delta files associated withdifferent storage times can include stored contents associated with thesame data files. For example, the delta files 790 and 790″ associatedwith storage times t₀ and t₂, respectively, both include stored contentsassociated with file identifier A. A coalesced delta file based on twoor more delta files that include the same changed locations for the samefile identifier can include the stored contents associated with thelatest storage time, i.e., the stored contents in the delta fileassociated with the latest storage time. For example with reference toFIG. 4, a coalesced delta file based on the delta files 790 and 790″ caninclude the contents of block 10 for file A stored in delta file 790″(which is associated with the later storage time t₂) and not thecontents of block 10 for file A stored in delta file 790 (which isassociated with the earlier storage time t₀). Based on coalescing two ormore delta files to generate a coalesced delta file, the commandcoordinator agent 540 can coalesce the corresponding first and secondindexes to associate the coalesced delta file with the coalesced changedlocations and the coalesced file identifiers.

As previously described, the command coordinator agent 540 can coalesce,i.e., merge, two or more delta files to generate a coalesced delta filebased on opening a coalesced delta file, coalescing the delta files, andwriting and/or otherwise providing the coalesced data to the coalesceddelta file. In some embodiments, the command coordinator agent 540 cancoalesce, i.e., merge, two or more delta files based on breaking thedelta files into two or more portions and iteratively coalescing theportions. For example, in one such embodiment, the command coordinatoragent 540 can separate, partition, and/or otherwise divide the deltafiles into portions, coalesce one of the portions, write and/orotherwise provide the coalesced portion to the coalesced file, deletethe portion, and iteratively return to coalescing the remainingportions. Iteratively coalescing portions of the delta files can reducedata storage capacity for coalescence. In embodiments in which portionsof delta files are iteratively coalesced, indexes corresponding to thecoalesced delta files can be updated based on the status of thecoalesced portions. For example, the indexes can be updated to refer tothe locations of the portions of the delta files and, based oncoalescing the portions, updated to refer to the coalesced delta file.

As previously described, in some embodiments, the backup servers 150,160 of the exemplary system 100 shown in FIG. 1A can be configured tostore backed up data with different terms of data retention. In suchembodiments, the first backup server 150 can be configured to store datafor a relatively short term, and the second backup server 160 can beconfigured to store data for a relatively long term. For example, thefirst backup server 150 can be configured to store data for one or moredays, weeks, or months, and the second backup server 160 can beconfigured to store data for one or more years. In some embodiments, thefirst backup server 150 can backup the data files maintained by the dataserver 130 and/or 140 based on a backup period and can provide thebacked up data to the second server 160 based on a data retention periodthat is greater than the backup period. Alternatively and/or incombination, in some embodiments, the first backup server 150 cancoalesce the backed up data based on a coalescence period that isgreater than the backup period and can provide the coalesced data to thesecond server 160. In one such embodiment, the backup period can be oneday, the coalescence period can be one week, and the retention periodcan be one month. In such an embodiment, the first backup server 150 canmaintain as many as three weekly-coalesced delta files and seven dailydelta files associated with a backup policy, and the backup server 160can maintain as many as fifty-two weekly-coalesced delta filesassociated with the same backup policy. Alternatively and/or incombination, in some embodiments, the second server 160 can coalesce thebacked up data provided by the first data server 150.

As will be understood by those of ordinary skill in the art, thedescribed systems and methods are not limited to using two backupservers 150, 160 that are associated with different terms of dataretention. For example, in some embodiments, the backup servers 150, 160can be configured to separately backup data files maintained by thefirst and second data servers 130, 140, respectively.

Using first and second indexes to associate stored contents with storagetimes, changed locations, and file identifiers can facilitate recreatingversions of data files. As previously described with respect to FIG. 2,the backup server 500 (e.g., one or more agents residing on the backupserver 500) can store delta files 590 and indexes 592, 594 on the backupstorage device 570. In some embodiments, copies of the indexes 592, 594can also be stored on the data storage device 470. In one suchembodiment, the data server 400 can facilitate a request to recreate aversion of a selected data file by using the indexes 592, 594 todetermine a storage time range for the version. Based on the storagetime range and the file identifier for the selected data file, the dataserver 400 can query the indexes 592, 594 to identify the changedlocations for the selected data file and the locations of thecorresponding stored contents in delta files associated with the indexes592, 594. Based on processing the indexes 592, 594, the data server 400can generate a request for the relevant portions of the relevant deltafiles from the backup server 500, and the backup server 500 can providethe relevant portions of the relevant delta files to the data server400.

Using first and second indexes to associate stored contents with storagetimes, changed locations, and file identifiers can also facilitaterecreating data files based on backed up data maintained by a relativelylong-term data storage device. As previously described with respect toFIG. 1A, the first backup server 150 and the first backup storage device155 can be configured to store data for a relatively short term, and thesecond backup server 160 and the second backup storage device 165 can beconfigured to store data for a relatively long term. In someembodiments, the first backup storage device 155 can be based onmagnetic disk, and the second backup storage device 165 can be based onmagnetic tape. Based on the schemes previously described, a requestingserver (e.g., the data server 130, 140 and/or the first backup server150) can generate a request for relevant portions of relevant deltafiles from the second backup server 160, and the second backup server160 can provide the relevant portions of the relevant delta files to therequesting server.

In some embodiments, backup server 150, 160 can access both of the datastorage devices 155, 165 associated with different terms of dataretention. For example, in some embodiments, backup server 150 can beconfigured to access backup storage device 155 (e.g., relatively shortterm data storage) and backup storage device 165 (e.g., relatively longterm data storage). Alternatively and/or in combination, in someembodiments, backup server 150 can access a single data storage devicehaving a data storage capacity allocated between relatively short termdata storage and relatively long term data storage.

The described restore and coalescence operations can provide backed updata to one or more servers. For example, in some embodiments, therestore and/or coalescence operation can transmit backed up data to oneor more data servers (e.g., a data server from which a request torestore a data file originated) and/or one or more backup servers (e.g.,a short term backup server and/or a long term backup server) connectedto and/or otherwise in communications with one or more datacommunications networks.

As previously described herein, data associated with a version of a datafile can be stored on one or more servers, such as one or more dataservers 400 (e.g., in an image 478) and/or one or more backup servers500 (e.g., in one or more delta files 590 and first and second indexes592, 594). In some embodiments, the described systems and methods canrestore a version of a data file based on a pre-determined spatialhierarchy. In one such spatial hierarchy, a request to restore a versionof a data file can be fulfilled based on accessing storage devices in alocal-to-remote order. As used herein, the term local can be interpretedto include nodes that are included in a LAN, and the term remote can beinterpreted to nodes that are not included in the LAN. For example,based on receiving a request from a client to restore a version of adata file, a data server can first determine whether one or more imagesstored on local storage devices include data sufficient to recreate theversion. Based on locally stored images not being sufficient to recreatethe version, the data server can communicate the request to one or moreother local servers (e.g., local backup servers capable of accessingrelatively short-term backed up data) and then directly and/orindirectly to one or more remote servers (e.g., remote backup serverscapable of accessing relatively long-term backed up data).

As previously described, a user can interact with the clients 110, 120,the data servers 130, 140, and/or the backup servers 150, 160 todetermine and/or otherwise select one or more policies (e.g., backuppolicies, restore policies, and coalescence policies 235, 335, 435, 535shown in FIGS. 1B, 1C, and 2), one or more data retention terms (e.g.,data retention terms for the first and second backup servers 150, 160shown in FIG. 1), and/or other parameters of interest. The user caninclude a system administrator and/or another entity.

A local user can interact with the clients 110, 120 by, for example,viewing a command line, using a graphical and/or other user interface,and entering commands via an input device, such as a mouse, a keyboard,a touch sensitive screen, a track ball, a keypad, etc. The userinterface can be generated by a graphics subsystem of the client 110,120, which renders the interface into an on- or off-screen surface(e.g., on a display device and/or in a video memory). Inputs from thelocal user can be received via an input/output (0/) subsystem and routedto a processor via an internal bus (e.g., a system bus) for executionunder the control of an operating system of the client 110, 120.

Similarly, a remote user can interact with the clients 110, 120 over thedata communications network 105. The inputs from the remote user an bereceived and processed in whole or in part by a remote digital dataprocessing device collocated with the remote user. Alternatively and/orin combination, the inputs can be transmitted back to and processed by alocal client 110, 120 or to another digital data processing device viaone or more networks using, for example, thin client technology. Theuser interface of the local client 110, 120 can also be reproduced, inwhole or in part, at the remote digital data processing devicecollocated with the remote user by transmitting graphics information tothe remote device and instructing the graphics subsystem of the remotedevice to render and display at least part of the interface to theremote user.

In one illustrative operation, a graphics subsystem of the client 110,120 can render and display a graphical user interface (including, forexample, one or more menus, windows, and/or other visual objects) on adisplay device associated with the client 110, 120 that can support thedefinition of one or more policies, one or more data retention terms,and/or other parameters of interest.

An illustrative display of a graphical user interface that canfacilitate a definition of a backup policy will now be described. Thoseof ordinary skill in the art will understand that the display should beinterpreted in an exemplary manner and that displays different than thatdescribed herein can be used within the scope of the present disclosure.For example, aspects, components, features, and/or modules of theillustrative display can be combined, separated, interchanged, and/orrearranged to generate other displays.

FIG. 5 shows an exemplary backup policy window 800 that can be used by auser (e.g., a system administrator and/or another entity) to determine abackup policy. As shown in FIG. 5A, the backup policy window 800 caninclude a data file selection region 810 and a storage time selectionregion 820.

The data file selection region 810 can include one or more features(e.g., pull-down menus, radio buttons, selectors, and/or fill-in boxes)for selecting files to be backed up. For example, as shown in FIG. 5,the data file selection region 810 can include radio buttons 820 forselecting files to be backed up, such as all data files or data files ofa specific type (e.g., operating system files), and a display 830 ofdata based on the data files maintained by a data server, such as dataserver 130. The display 830 can present data based on the directories,subdirectories, and other file structures maintained by the data server130 on data storage device 135. For example, as shown in FIG. 5, thedisplay 830 presents a data structure 835 having data files arranged ina directory and subdirectory structure. A user may select one or moredata files to be backed up by, for example, selecting the files with amouse click, drawing a box around the files, etc. For example, datafiles included in the box 840 represent data files selected by a userfor backup and association with a backup policy. Unselected files can beexcluded from backup and/or can be associated with different backuppolicies.

The storage time selection region 850 can include one or more features(e.g., pull-down menus, radio buttons, selectors, and/or fill-in boxes)for determining the storage times for the data files selected in box840. For example, as shown in FIG. 5, the storage time selection region850 can provide selectors 860 and pull-down menus 865 associated withdifferent storage times, such as continuous storage times (which can beunderstood to refer to backup of the data files 840 substantiallycontemporaneously with changed locations to the data files 840),periodic storage times (e.g., daily and weekly as shown in FIG. 5), andcustom storage times 870 (e.g., daily on Monday-Friday at 6:00 AM anddaily on Saturday-Sunday at 8:00 AM).

As will be understood by those of ordinary skill in the art, displayssimilar to those shown in FIG. 5 can be provided to allow a user todetermine and/or otherwise select other parameters of interest, e.g., arestore policy, a coalescence policy, and a data retention term. Forexample, for a restore policy, a user can select one or more versions ofone or more data files to be restored, one or more locations to which torestore the versions, and one or more times corresponding to theversions, i.e., past times; for a coalescence policy, a user can selecta storage time range of delta files to be coalesced and/or a storagecapacity threshold for initiating a coalescence; and, for a dataretention term, a user can select a time interval for retaining backedup data.

The systems and methods described herein are not limited to a hardwareor software configuration; they can find applicability in many computingor processing environments. The systems and methods can be implementedin hardware or software, or in a combination of hardware and software.The systems and methods can be implemented in one or more computerprograms, in which a computer program can be understood to comprise oneor more processor-executable instructions. The computer programs canexecute on one or more programmable processors, and can be stored on oneor more storage media readable by the processor, comprising volatile andnon-volatile memory and/or storage elements.

The computer programs can be implemented in high level procedural orobject oriented programming language to communicate with a computersystem. The computer programs can also be implemented in assembly ormachine language. The language can be compiled or interpreted. Thecomputer programs can be stored on a storage medium or a device (e.g.,compact disk (CD), digital video disk (DVD), magnetic disk, internalhard drive, external hard drive, random access memory (RAM), redundantarray of independent disks (RAID), or removable memory device) that isreadable by a general or special purpose programmable computer forconfiguring and operating the computer when the storage medium or deviceis read by the computer to perform the methods described herein.

References to a network, unless provided otherwise, can include one ormore intranets and/or the Internet. References herein to microprocessorinstructions or microprocessor-executable instructions, in accordancewith the above, can be understood to include programmable hardware.

References to “a microprocessor” and “a processor”, or “themicroprocessor” and “the processor,” can be understood to include one ormore microprocessors that can communicate in a stand-alone and/or adistributed environment(s), and can thus can be configured tocommunicate via wired or wireless communications with other processors,where such one or more processor can be configured to operate on one ormore processor-controlled devices that can be similar or differentdevices. Use of such “microprocessor” or “processor” terminology canthus also be understood to include a central processing unit, anarithmetic logic unit, an application-specific integrated circuit (IC),and/or a task engine, with such examples provided for illustration andnot limitation.

Furthermore, references to memory, unless otherwise specified, caninclude one or more processor-readable and accessible memory elementsand/or components that can be internal to the processor-controlleddevice, external to the processor-controlled device, and/or can beaccessed via a wired or wireless network using a variety ofcommunications protocols, and unless otherwise specified, can bearranged to include a combination of external and internal memorydevices, where such memory can be contiguous and/or partitioned based onthe application. Accordingly, references to a database can be understoodto include one or more memory associations, where such references caninclude commercially available database products (e.g., SQL, Informix,Oracle) and also proprietary databases, and may also include otherstructures for associating memory such as links, queues, graphs, trees,with such structures provided for illustration and not limitation.

Unless otherwise stated, use of the word “substantially” can beconstrued to include a precise relationship, condition, arrangement,orientation, and/or other characteristic, and deviations thereof asunderstood by one of ordinary skill in the art, to the extent that suchdeviations do not materially affect the disclosed methods and systems.

Throughout the entirety of the present disclosure, use of the articles“a” or “an” to modify a noun can be understood to be used forconvenience and to include one, or more than one of the modified noun,unless otherwise specifically stated.

Elements, components, modules, and/or parts thereof that are describedand/or otherwise portrayed through the figures to communicate with, beassociated with, and/or be based on, something else, can be understoodto so communicate, be associated with, and or be based on in a directand/or indirect manner, unless otherwise stipulated herein.

While the systems and methods described herein have been shown anddescribed with reference to the shown embodiments, those of ordinaryskill in the art will recognize or be able to ascertain many equivalentsto the embodiments described herein by using no more than routineexperimentation. Such equivalents are intended to be encompassed by thescope of the present disclosure and the appended claims. Accordingly,the systems and methods described herein are not to be limited to theembodiments described herein, can comprise practices other than thosedescribed, and are to be interpreted as broadly as allowed underprevailing law.

1. (canceled)
 2. The method of claim 63, wherein the target storagetimes are based on one or more of: an actual time, a time interval, andan event. 3-9. (canceled)
 10. The method of claim 61, wherein storingthe contents includes: selecting at least one memory to store thecontents.
 11. The method of claim 10, wherein selecting at least onememory includes: selecting the at least one memory to be distinct from apreviously selected memory associated with a prior target storage time.12. (canceled)
 13. The method of claim 63, wherein providing theassociations includes: generating one or more indexes to associate: thestored contents, the respective target storage times, the respectivechanged locations, and one or more respective file identifiers.
 14. Themethod of claim 13, wherein the one or more indexes include: a firstindex to the changed locations based on the one or more fileidentifiers, and a second index to the stored contents based on thechanged locations.
 15. The method of claim 61, further comprising: usingthe stored contents to create a version of a selected one of the one ormore source data files.
 16. The method of claim 15, wherein using thestored contents to create a version includes: for each of one or moretarget storage times associated with the version: querying one or moreindexes that associate the stored contents, the respective targetstorage times, the respective changed locations, and one or morerespective file identifiers, to identify stored contents and respectivechanged locations associated with the selected data file, and combiningthe identified stored contents with data from a baseline imageassociated with the selected data file.
 17. The method of claim 16,wherein querying includes: determining that the changed locations arethe same for two or more different target storage times, and,identifying the stored contents of the changed locations associated withthe latest of the two or more different target storage times.
 18. Themethod of claim 63, further comprising: receiving from a first server arequest to create a version of a selected one of the one or more sourcedata files, and based on the request: for each of one or more targetstorage times associated with the version: querying one or more indexesthat associate the stored contents, the respective target storage times,the respective changed locations, and one or more respective fileidentifiers, to identify stored contents and respective changedlocations associated with the selected data file, and providing theidentified stored contents and respective changed locations to the firstserver.
 19. The method of claim 18, further comprising: at the firstserver, combining the identified stored contents with data from abaseline image associated with the selected data file.
 20. The method ofclaim 63, further comprising: at a coalescence time, coalescing: two ormore stored contents associated with the same file and two or moredifferent target storage times, the respective changed locationsassociated with the two or more coalesced contents, and one or moreindexes to associate the coalesced contents, the respective coalescedchanged locations, an identifier of the file with which those contentsare associated, and the latest of the two or more different targetstorage times.
 21. The method of claim 63, further comprising: at acoalescence time, coalescing: two or more stored contents associatedwith the same file and the same target storage time, the respectivechanged locations associated with the two or more coalesced contents,and one or more indexes to associate the coalesced contents, therespective coalesced changed locations, an identifier of the file withwhich those contents are associated, and the same target storage time.22. The method of claim 21, wherein the coalescence time is based on oneor more of: an actual time, a time interval, and an event.
 23. Themethod of claim 22, wherein the event includes an event based on anavailable storage capacity of a storage medium. 24-37. (canceled) 38.The storage medium of claim 66, wherein the target storage times arebased on one or more of: an actual time, a time interval, and an event.39. (canceled)
 40. The storage medium of claim 64, wherein theinstructions to store the contents include instructions to select atleast one memory to store the contents.
 41. The storage medium of claim40, wherein the instructions to select at least one memory includeinstructions to select the at least one memory to be distinct from apreviously selected memory associated with a prior target storage time.42. (canceled)
 43. The storage medium of claim 66, wherein theinstructions to provide the associations include instructions togenerate one or more indexes to associate: the stored contents, therespective target storage times, the respective changed locations, andone or more respective file identifiers.
 44. The storage medium of claim43, wherein the one or more indexes include: a first index to thechanged locations based on the one or more file identifiers, and asecond index to the stored contents based on the changed locations. 45.The storage medium of claim 64, further comprising instructions to usethe stored contents to create a version of a selected one of the one ormore source data files.
 46. The storage medium of claim 45, wherein theinstructions to use the stored contents to create a version includeinstructions to: for each of one or more target storage times associatedwith the version: query one or more indexes that associate the storedcontents, the respective arget storage times, the respective changedlocations, and one or more respective file identifiers, to identifystored contents and respective changed locations associated with theselected data file, and combine the identified stored contents with datafrom a baseline image associated with the selected data file.
 47. Thestorage medium of claim 64, further comprising instructions to receivefrom a first server a request to create a version of a selected one ofthe one or more source data files, and based on the request: for each ofone or more target storage times associated with the version: query oneor more indexes that associate the stored contents, the respectivetarget storage times, the respective changed locations, and one or morerespective file identifiers, to identify stored contents and respectivechanged locations associated with the selected data file, and providethe identified stored contents and respective changed locations to thefirst server.
 48. The storage medium of claim 47, further comprisinginstructions to, at the first server, combine the identified storedcontents with data from a baseline image associated with the selecteddata file.
 49. (canceled)
 50. The system of claim 69, wherein the targetstorage times are based on one or more of: an actual time, a timeinterval, and an event.
 51. (canceled)
 52. The system of claim 67,wherein at least one of the agents selects at least one memory to storethe contents.
 53. The system of claim 52, wherein the at least onememory is distinct from a previously selected memory associated with aprior target storage time.
 54. (canceled)
 55. The system of claim 69,wherein at least one of the agents provides the associations bygenerating one or more indexes to associate: the stored contents, therespective target storage times, the respective changed locations, andthe respective one or more respective file identifiers.
 56. The systemof claim 55, wherein the one or more indexes include: a first index tothe changed locations based on the one or more file identifiers, and asecond index to the stored contents based on the changed locations. 57.The system of claim 69, further configured comprising to use the storedcontents to create a version of a selected one of the one or more sourcedata files.
 58. The system of claim 57, wherein the system is configuredto use the stored contents to create a version by: for each of one ormore target storage times associated with the version: querying one ormore indexes that associate the stored contents, the respective targetstorage times, the respective changed locations, and one or morerespective file identifiers, to identify stored contents and respectivechanged locations associated with the selected data file, and combinethe identified stored contents with data from a baseline imageassociated with the selected data file.
 59. The system of claim 69,further configured to receive from a first server a request to create aversion of a selected one of the one or more source data files, andbased on the request: for each of one or more storage times associatedwith the version: query one or more indexes that associate the storedcontents, the respective arget storage times, the respective changedlocations, and one or more respective file identifiers, to identifystored contents and respective changed locations associated with theselected source data file, and provide the identified stored contentsand respective changed locations to the first server.
 60. The system ofclaim 59, further configured to, at the first server, combine theidentified stored contents with data from a baseline image associatedwith the selected source data file.
 61. A method for maintaining, in astorage system having a source storage system and target storage system,information from which a set of source files stored on the sourcestorage system can be retrieved, the method comprising storing baselineimages of one or more source data files in target files of the targetstorage system, and for each of a sequence of target storage times: A)dynamically identifying locations in the source storage system wherechanges have been made since the previous target storage time; and B) inresponse to identifying the locations, i) reading at that target storagetime contents that occupy the locations, and ii) sending the contents tothe target storage system; and C) storing the contents in the targetstorage system together with associations of the contents with thelocations.
 62. The method of claim 61, wherein the associations of thecontents with the locations associate the contents with the files in thesource storage system to which those contents were written.
 63. Themethod of claim 62, further comprising providing in the target storagesystem associations between the contents there stored and the targetstorage times for which those contents were stored.
 64. A storage mediumcontaining instructions readable by a computer system that comprises asource storage system and a target storage system, the instructionscomprising instructions to configure the computer system to maintain inthe target storage system information from which a set of source filesstored on the source storage system can be retrieved, and instructionsto configure the computer system to store baseline images of one or moresource data files in target files of the target storage system, andinstructions to configure the computer system for each of a sequence oftarget storage times to: A) dynamically identify locations in the sourcestorage system where changes have been made since the previous targetstorage time; and B) in response to identifying the locations, i) readat that target storage time contents that occupy the locations, and ii)send the contents to the target storage system; and C) store thecontents in the target storage system together with associations of thecontents with the locations.
 65. The storage medium of claim 64, whereinthe associations of the contents with the locations associate thecontents with the files in the source storage system to which thosecontents were written.
 66. The storage medium of claim 65, wherein theinstructions further configure the computer system to provide in thetarget storage system associations between the contents there stored andthe target storage times for which those contents were stored.
 67. Acomputer system comprising a source storage system and a target storagesystem in which information is maintained from which a set of sourcefiles stored on the source storage system can be retrieved, the systembeing configured to execute agents that perform operations comprising:storing baseline images of one or more source data files in target filesof the target storage system, and for each of a sequence of targetstorage times: A) dynamically identifying locations in the sourcestorage system where changes have been made since the previous targetstorage time; and B) in response to identifying the locations, i)reading at that target storage time contents that occupy the locations,and ii) sending the contents to the target storage system; and C)storing the contents in the target storage system together withassociations of the contents with the locations.
 68. The system of claim67, wherein the associations of the contents with the locationsassociate the contents with the files in the source storage system towhich those contents were written.
 69. The system of claim 68, whereinat least one of the agents provides in the target storage systemassociations between the contents there stored and the target storagetimes for which those contents were stored.
 70. The method of claim 61,wherein dynamically identifying the locations further comprises: at atime prior to that target storage time, storing a baseline image of atleast the one or more source data files, and using one or more dataintegrity procedures to generate a baseline summary comprising a summaryof the baseline image; and thereafter, storing a second image of atleast the one or more source data files, using one or more dataintegrity procedures to generate a second image summary comprising asummary of the second image, and based on the baseline summary and thesecond image summary, determining whether the one or more source datafiles includes changed locations.
 71. The storage medium of claim 64,wherein the instructions to dynamically identify locations furthercomprises: instructions at a time prior to that target storage time to:store a baseline image of at least the one or more source data files,and use one or more data integrity procedures to generate a baselinesummary comprising a summary of the baseline image; and thereafter,store a second image of at least the one or more source data files, useone or more data integrity procedures to generate a second image summarycomprising a summary of the second image, and based on the baselinesummary and the second image summary, determine whether the one or moresource data files includes changed locations.
 72. The system of claim67, wherein dynamically identifying locations further comprises: at atime prior to the target storage time, storing a baseline image of atleast the one or more source data files, and using one or more dataintegrity procedures to generate a baseline summary comprising a summaryof the baseline image; and thereafter, storing a second image of atleast the one or more source data files, using one or more dataintegrity procedures to generate a second image summary comprising asummary of the second image, and based on the baseline summary and thesecond image summary, determining whether the one or more source datafiles includes changed locations.
 73. A method for performing operationson data files, the method comprising: defining a policy file having dataabout a policy, the data comprising information for identifying a set ofdata files with which the policy is associated, identification of atleast one operation with which the policy is associated, and at least aselected time for executing the at least one operation associated withthe policy; and at the selected time, executing an operation with whichthe selected time is associated on the set of data files identified bythe information.
 74. A storage medium containing instructions readableby a computer system, the instructions comprising instructions toconfigure the computer system to: define a policy file having data abouta policy, the data comprising information for identifying a set of datafiles with which the policy is associated, identification of at leastone operation with which the policy is associated, and at least aselected time for executing the at least one operation associated withthe policy; and at the selected time, execute an operation with whichthe selected time is associated on the set of data files identified bythe information.
 75. A computer system that is configured to executeagents that perform operations, the operations comprising: defining apolicy file having data about a policy, the data comprising informationfor identifying a set of data files with which the policy is associated,identification of at least one operation with which the policy isassociated, and at least a selected time for executing the at least oneoperation associated with the policy; and at the selected time,executing an operation with which the selected time is associated on theset of data files identified by the information.
 76. The method of claim61, further comprising generating the baseline image, wherein thegenerating further comprises generating one or more of a volume image, afile image, and a snapshot image.
 77. A method for maintaining, in astorage system having a source storage system and a backup storagesystem, information from which a set of source files stored on thesource storage system can be retrieved, the method comprising storingbaseline images of one or more source data files in backup files of thebackup storage system, and for a selected backup storage time: A)dynamically identifying locations in the source storage system wherechanges have been made since a previous backup storage time; and B) inresponse to identifying the locations, i) reading contents that occupythe locations, and ii) sending the contents to the backup storagesystem; and C) storing the contents in the backup storage systemtogether with associations of the contents with the locations.
 78. Acomputer system comprising a source storage system and a backup storagesystem in which information is maintained from which a set of sourcefiles stored on the source storage system can be retrieved, the systembeing configured to execute agents that perform operations comprising:storing baseline images of one or more source data files in backup filesof the backup storage system, and for a selected backup storage time: A)dynamically identifying locations in the source storage system wherechanges have been made since a previous backup storage time; and B) inresponse to identifying the locations, i) reading contents that occupythe locations, and ii) sending the contents to the backup storagesystem; and C) storing the contents in the backup storage systemtogether with associations of the contents with the locations.
 79. Astorage medium containing instructions readable by a computer systemthat comprises a source storage system and a backup storage system, theinstructions comprising instructions to configure the computer system tomaintain in the backup storage system information from which a set ofsource files stored on the source storage system can be retrieved, andinstructions to configure the computer system to store baseline imagesof one or more source data files in backup files of the backup storagesystem, and instructions to configure the computer system for a selectedbackup storage time to: A) dynamically identify locations in the sourcestorage system where changes have been made since a previous backupstorage time; and B) in response to identifying the locations, i) readcontents that occupy the locations, and ii) send the contents to thebackup storage system; and C) store the contents in the backup storagesystem together with associations of the contents with the locations.80. A method for maintaining, in a storage system having a sourcestorage system and a target storage system, information from which a setof source files stored on the source storage system can be retrieved,the method comprising storing baseline images of one or more source datafiles in target files of the target storage system, and for a selectedtarget storage time: A) dynamically identifying locations in the sourcestorage system where changes have been made since a previous targetstorage time; and B) in response to identifying the locations, i)reading contents that occupy the locations, and ii) sending the contentsto the target storage system; and C) storing the contents in the targetstorage system together with associations of the contents with thelocations.
 81. A computer system comprising a source storage system anda target storage system in which information is maintained from which aset of source files stored on the source storage system can beretrieved, the system being configured to execute agents that performoperations comprising: storing baseline images of one or more sourcedata files in target files of the target storage system, and for aselected target storage time: A) dynamically identifying locations inthe source storage system where changes have been made since a previoustarget storage time; and B) in response to identifying the locations, i)reading contents that occupy the locations, and ii) sending the contentsto the target storage system; and C) storing the contents in the targetstorage system together with associations of the contents with thelocations.
 82. A storage medium containing instructions readable by acomputer system that comprises a source storage system and a targetstorage system, the instructions comprising instructions to configurethe computer system to maintain in the target storage system informationfrom which a set of source files stored on the source storage system canbe retrieved, and instructions to configure the computer system to storebaseline images of one or more source data files in target files of thetarget storage system, and instructions to configure the computer systemfor a selected target storage time to: A) dynamically identify locationsin the source storage system where changes have been made since aprevious target storage time; and B) in response to identifying thelocations, i) read contents that occupy the locations, and ii) send thecontents to the target storage system; and C) store the contents in thetarget storage system together with associations of the contents withthe locations.